The four major purposes of this research project are: 1) To define the effects of parathyroid hormone, calcitonin, corticosteroid, vitamin D metabolites, and diphosphonates upon the bone remodeling sequence in alveolar bone of the rat during the process of tooth (molar) drift in this organ; 1) To study the turnover of nuclei in osteoclasts in remodeling foci in the alveolar bone and particularly by using 3H-thymidine as a nuclear marker determine the uptake and release of individual nuclei by osteoclasts; 3) By use of immunofluorescent methods determine the effects of the various hormones upon cAMP content of the various cell types involved in the remodeling sequence; and 4) By use of the Hanning Free Flow electrophoresis technique to see if one can isolate peripheral monocytes from human and animal blood, and stimulate these cells to undergo mitosis, cell division, and modulation into osteoclasts either by the use of parathyroid hormone, osteoclast stimulating factor, and/or incubation and culture of these cells in the presence of bone fragments or collagen substrata.